Coastal zones are characterized by the interactions between continents and oceans and, therefore, between fresh and salt surface and groundwater. The wetlands of coastal zones represent transitional ecosystems that are affected by these conditions, although little is known about the hydrogeochemistry of wetlands, especially coastal wetlands. In the present study, the hydrogeochemical characterization of coastal freshwater herbaceous wetlands in the Ciénaga del Fuerte Protected Natural Area in Veracruz, Mexico, in the American tropics was carried out per plant community. Four herbaceous wetlands (alligator flag, saw grass, cattail, and floodplain pasture) were monitored to understand the origin of the water feeding these ecosystems, the hydrogeochemical composition of groundwater, and the relationship between the groundwater and ecology of these ecosystems during dry and rainy seasons. The results indicate that Ciénaga del Fuerte is located in a regional discharge area and receives local recharge, so it is fed by both regional and local flows. The chemical composition varied temporally and spatially, creating unique conditions that determined the habitat occupied by the hydrophytic vegetation. The spatiotemporal behaviour of groundwater is one factor that, along with the hydroperiod, determines wetland dynamics and affects wetland biota (ecohydrogeochemistry). Generalist plant communities established in zones of local recharge, whereas other more specialized and/or plastic communities inhabited zones receiving regional flows with greater ion concentrations. This information forms the basis for establishing an appropriate scale (municipal, state, or larger regions) for the sustainable management of goods and services provided by the wetlands.

Antelope grass (Echinochloa pyramidalis) is an African grass species used for cattle grazing in Mexican wetlands. It has been introduced because of its tolerance to flooding and is now a widespread invasive. In this work, we present the advances of a freshwater marsh restoration project represented by bulltongue (Sagittaria lancifolia) but invaded by antelope grass. This project began in 2007 with the goals of eliminating antelope grass and other problematic species, increasing the cover of the native vegetation, and recovering habitat for waterfowl. Two sets of controls were established (in the remaining marsh and the inundated grassland) along with three other managed sites (variations of clipping by hand, drowning the cut plants, burning, covering with black plastic, or selectively applying herbicide). With two years of restoration activities, the antelope grass was almost completely eliminated, remaining only in one control set. The dry conditions of 2009 have favored the resprouting of the invader, but it still has low cover values. Pickerelweed (Pontederia sagittata), cattail (Typha domingensis), and bulltongue have appeared with high cover values in most of the quadrats in almost all sites. Plant species richness has increased with time. Amphibians and reptiles have varied through time but are showing a slight increasing trend.

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